High temperature thermal expansion and electrical conductivity of Ln0.95MnO3+δ (Ln=La, Nd or Gd)

Wandekar, R.V.; Wani, B.N.; Bharadwaj, S.R.

doi:10.1016/j.jallcom.2006.06.063

Cited by 12 publications

(2 citation statements)

References 28 publications

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“…No discernable trend could be identified for substitution of the A-site from La to Dy [74][75][76][77][78][79][80] (Figure 2g) under the caveat that some of the data was only available for temperatures >300 K (Table A2). For the ORR data of Suntivich et al [22], the activity trend matches that of the typical conductivity of the used LaBO 3 perovskites.…”

Section: Effect Of Chemical Substitution On Activitymentioning

confidence: 99%

Perovskite Electrocatalysts for the Oxygen Reduction Reaction in Alkaline Media

Risch

2017

Catalysts

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Abstract:Oxygen reduction is considered a key reaction for electrochemical energy conversion but slow kinetics hamper application in fuel cells and metal-air batteries. In this review, the prospect of perovskite oxides for the oxygen reduction reaction (ORR) in alkaline media is reviewed with respect to fundamental insight into activity and possible mechanisms. For gaining these insights, special emphasis is placed on highly crystalline perovskite films that have only recently become available for electrochemical interrogation. The prospects for applications are evaluated based on recent progress in the synthesis of perovskite nanoparticles. The review concludes with the current understanding of oxygen reduction on perovskite oxides and a perspective on opportunities for future fundamental and applied research.

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Section: Effect Of Chemical Substitution On Activitymentioning

confidence: 99%

Perovskite Electrocatalysts for the Oxygen Reduction Reaction in Alkaline Media

Risch

2017

Catalysts

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“…LaMnO 3 2θ 22.9 (d=3.88, (110)), 32.6 (d=2.74, (211)), 40.2 (d=2.24, (200)), 46.9 (d=1,94, (220)), 52.7 (d=1.63, (211)), 58.1 (d=1.59, (211)) and 68.2 o (d=1.37, (422)). 15 It can be observed, however, a gradual shift of the XRD peaks to lower diffraction angles as a function of the increasing concentration of iron. Such change is also present in the cell parameters determined for perovskites having different compositions (see Table 1), suggesting a gradual incorporation of Fe into the perovskite structures.…”

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confidence: 94%

LaFe xMn yMo zO 3 catalysts for the oxidation of volatile aromatic organic contaminants

Tristão¹,

Ardisson²,

Macedo³

et al. 2007

J. Braz. Chem. Soc.

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Novas perovskitas mistas LaFe x Mn y Mo z O 3 foram preparadas, caracterizadas e investigadas como catalisadores para a oxidação total de tolueno, usado como composto orgânico aromático volátil (COV aromático) modelo. As perovskitas foram caracterizadas por DRX (Difratometria de Raios X), RTP (Redução a Temperatura Programada), determinação de área superficial BET e espectroscopia Mössbauer. Os dados obtidos indicaram a formação da fase perovskita e a incorporação de todos os metais na estrutura. As reações catalíticas foram realizadas em um sistema de Reação a Temperatura Programada com tolueno (1000 ppm) e ar sintético em fase gasosa. Foi observado que a oxidação do tolueno inicia-se a 280 o C e que Mn é o principal responsável pela atividade catalítica. No entanto, a presença de pequenas quantidades de Fe (LaFe 0,27 Mn 0,73 O 3 ) resulta em um importante aumento nessa atividade. Estudos de tempo de vida mostraram que os catalisadores são estáveis mesmo após 100 h de reação a 400 o C e nenhuma alteração estrutural significativa foi observada por DRX e Mössbauer.New mixed perovskites LaFe x Mn y Mo z O 3 were prepared, characterized and investigated as catalysts for the total oxidation of the model aromatic VOC (Volatile Organic Compound), toluene. The perovskites were characterized by XRD (X-Ray Diffractometry), Mössbauer spectroscopy, TPR (Temperature Programmed Reduction) and BET surface area determination. The results suggested the formation of the perovskite phase with incorporation of all metals in the structure. The catalytic studies were carried out in a Temperature Programmed Reaction system with toluene (1000 ppm) and synthetic air in the gas phase. It was observed that the oxidation of toluene starts at temperature as low as 280 °C and that Mn is responsible for most of the catalytic activity. However, the presence of small amounts of Fe (LaFe 0.27 Mn 0.73 O 3 ) leads to an increase in this activity. Stability studies showed that these perovskite catalysts are stable even after 100 h reaction at 400 o C with no significant structural change, as observed by XRD and Mössbauer analyses.Keywords: lanthanum iron perovskite, toluene oxidation, catalytic oxidation, manganese, molybdenum IntroductionPerovskite type oxides, ABO 3 , have been extensively investigated as catalysts for several processes including fuel cells, 1 water dissociation, 2 hydrogenation and hydrogenolysis, 3 ammonia oxidation 4 and NO x reduction. 5 Several reviews covering these fields can be found in the literature. 6,7 Perovskites, especially LaMnO 3 , have also been used in environmental applications, e.g. the oxidation of hydrocarbons, 8-10 chlorinated organics 11 and H 2 O 2 reactions. 6,12 LaMnO 3 shows good stability and flexible oxygen stoichiometry ( ) with different Mn oxidation states, i.e. Mn 2+ , Mn 3+ , Mn 4+ , which strongly affects the catalytic behavior. Also, the isomorphic substitution of metals in the perovskite structure allows a control of the catalytic properties of the material. Several LaMnO 3 1525 Tristão et a...

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